Re: [EE] DAC-to-headphone-level output amp
"Harold Hallikainen" <[email protected]>
| Newsgroups | gmane.comp.hardware.microcontrollers.pic |
|---|---|
| Message-ID | <[email protected]> |
I wonder if the BlueTooth transmitter already has a DC blocking capacitor on its input. If the circuitry in the BT device is single ended, it probably DC blocks and then biases to the ADC midrange voltage. It would be interesting to try it with no additional capacitor. Harold The ideal design has zero parts. On Thu, December 19, 2024 5:59 pm, [email protected] wrote: > > For a one off I would try direct drive the BLE from the DAC via a 10uF > capacitor and work out where to go from there. > > > Cheers, > Martin. > > > On Friday, 20 December 2024 at 09:58, Neil <[email protected]> wrote: > >> I'm designing a one-off device for myself that will generate audio from >> a microcontroller and I want to send that audio to a small BLE audio >> transmitter (something I picked up on Amazon). >> The BLE transmitter has a 3.5mm headphone plug and they specify it's for >> "Aux" level devices, but works very well when plugged into my PC or >> cellphone, so I take that to mean headphone level. >> FWIW, the audio signal is mono, but I want to drive both left and right >> channels. >> >> Researching online gets me a whole lot of different answers -- >> everything from line level being 10k ohms input impedance and 1V or 2V >> to 3V and headphone level is 8 to 600 ohms, with voltage level from 0.3 >> to 0.8V (though I would've expected headphone level to be higher since >> it's amplified). >> >> Can anyone shed some light on this please. I'm unsure what I'd be >> designing for... should I just do an op-amp with a very low output >> impedance and adjustable volume until it sounds decent? Or is there a >> spec I should follow? >> Alternately, I'd be happy if there's some simple monolithic chip that >> would do this for me (take a 0V-3.3V audio signal from a uC DAC and >> convert it to headphone level audio). >> >> Cheers, >> -Neil. >> >> >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> https://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > https://mailman.mit.edu/mailman/listinfo/piclist > -- Not sent from an iPhone.